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                <h1 id="《剑指offer》算法-—-基于JS实现代码"><a href="#《剑指offer》算法-—-基于JS实现代码" class="headerlink" title="《剑指offer》算法 — 基于JS实现代码"></a>《剑指offer》算法 — 基于JS实现代码</h1><h2 id="按照书中题目的顺序26-30题目"><a href="#按照书中题目的顺序26-30题目" class="headerlink" title="按照书中题目的顺序26-30题目"></a>按照书中题目的顺序26-30题目</h2><blockquote>
<h2 id="26-二叉搜索树与双向链表"><a href="#26-二叉搜索树与双向链表" class="headerlink" title="26.二叉搜索树与双向链表"></a>26.二叉搜索树与双向链表</h2><blockquote>
<p>输入一棵二叉搜索树，将该二叉搜索树转换成一个排序的双向链表。要求不能创建任何新的结点，只能调整树中结点指针的指向。<br>方法一：递归+数组</p>
<p>解题思路：</p>
<ul>
<li>中序遍历一遍二叉搜索树，将节点保存在一个数组中。</li>
<li>遍历数组，更改每个节点的 left 和 right</li>
<li>返回数组第一个元素<br>时间复杂度是 O(N)，空间复杂度是 O(N)。相较于方法二，多开辟了 O(N)的数组空间。</li>
</ul>
</blockquote>
<pre class="line-numbers language-js" data-language="js"><code class="language-js"><span class="token comment">/* function TreeNode(x) &#123;
    this.val = x;
    this.left = null;
    this.right = null;
&#125; */</span>
<span class="token keyword">function</span> <span class="token function">Convert</span><span class="token punctuation">(</span><span class="token parameter">pRootOfTree</span><span class="token punctuation">)</span> <span class="token punctuation">&#123;</span>
  <span class="token comment">// write code here</span>
  <span class="token keyword">if</span> <span class="token punctuation">(</span><span class="token operator">!</span>pRootOfTree<span class="token punctuation">)</span> <span class="token punctuation">&#123;</span>
    <span class="token keyword">return</span> <span class="token keyword">null</span><span class="token punctuation">;</span>
  <span class="token punctuation">&#125;</span>
  <span class="token keyword">const</span> nodes <span class="token operator">=</span> <span class="token punctuation">[</span><span class="token punctuation">]</span><span class="token punctuation">;</span>
  <span class="token function">midTravel</span><span class="token punctuation">(</span>pRootOfTree<span class="token punctuation">,</span> nodes<span class="token punctuation">)</span><span class="token punctuation">;</span>
  <span class="token keyword">const</span> len <span class="token operator">=</span> nodes<span class="token punctuation">.</span>length<span class="token punctuation">;</span>
  <span class="token keyword">for</span> <span class="token punctuation">(</span><span class="token keyword">let</span> i <span class="token operator">=</span> <span class="token number">0</span><span class="token punctuation">;</span> i <span class="token operator">&lt;</span> len<span class="token punctuation">;</span> i<span class="token operator">++</span><span class="token punctuation">)</span> <span class="token punctuation">&#123;</span>
    nodes<span class="token punctuation">[</span>i<span class="token punctuation">]</span><span class="token punctuation">.</span>right <span class="token operator">=</span> nodes<span class="token punctuation">[</span>i <span class="token operator">+</span> <span class="token number">1</span><span class="token punctuation">]</span> <span class="token operator">||</span> <span class="token keyword">null</span><span class="token punctuation">;</span>
    nodes<span class="token punctuation">[</span>i<span class="token punctuation">]</span><span class="token punctuation">.</span>left <span class="token operator">=</span> nodes<span class="token punctuation">[</span>i <span class="token operator">-</span> <span class="token number">1</span><span class="token punctuation">]</span> <span class="token operator">||</span> <span class="token keyword">null</span><span class="token punctuation">;</span>
  <span class="token punctuation">&#125;</span>
  <span class="token keyword">return</span> nodes<span class="token punctuation">[</span><span class="token number">0</span><span class="token punctuation">]</span><span class="token punctuation">;</span>
<span class="token punctuation">&#125;</span>

<span class="token comment">//中序遍历,将所有节点存在nodes中</span>
<span class="token keyword">function</span> <span class="token function">midTravel</span><span class="token punctuation">(</span><span class="token parameter">node<span class="token punctuation">,</span> nodes</span><span class="token punctuation">)</span> <span class="token punctuation">&#123;</span>
  <span class="token keyword">if</span> <span class="token punctuation">(</span>node<span class="token punctuation">.</span>left<span class="token punctuation">)</span> <span class="token punctuation">&#123;</span>
    <span class="token function">midTravel</span><span class="token punctuation">(</span>node<span class="token punctuation">.</span>left<span class="token punctuation">,</span> nodes<span class="token punctuation">)</span><span class="token punctuation">;</span>
  <span class="token punctuation">&#125;</span>
  nodes<span class="token punctuation">.</span><span class="token function">push</span><span class="token punctuation">(</span>node<span class="token punctuation">)</span><span class="token punctuation">;</span>
  <span class="token keyword">if</span> <span class="token punctuation">(</span>node<span class="token punctuation">.</span>right<span class="token punctuation">)</span> <span class="token punctuation">&#123;</span>
    <span class="token function">midTravel</span><span class="token punctuation">(</span>node<span class="token punctuation">.</span>right<span class="token punctuation">,</span> nodes<span class="token punctuation">)</span><span class="token punctuation">;</span>
  <span class="token punctuation">&#125;</span>
<span class="token punctuation">&#125;</span><span aria-hidden="true" class="line-numbers-rows"><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span></span></code></pre>

<blockquote>
<p>方法二：一次递归<br>二叉搜索树的性质是：左节点 &lt; 当前节点 &lt; 右节点。转换后的双向链表是有序的，这里采用中序递归遍历保证有序性。</p>
<p>设计的递归函数返回的是：已转换好的双向链表的尾结点，也就是当前节点的 left 指针应该指向的地方。递归函数的实现思路：</p>
<ul>
<li>检查 left 是否为空，不为空，那么递归调用（传入左子树）</li>
<li>将 left 指针指向已转换好的双向链表的尾结点，并将尾节点的 right 指向当前节点</li>
<li>更新双向链表尾节点（变为当前节点），检查 right 是否为空，不为空，递归调用传入右子树）</li>
<li>返回转换后的双向链表尾节点<br>整个过程的要递归遍历一遍二叉树，时间复杂度是 O(N)，空间复杂度是 O(N)。</li>
</ul>
</blockquote>
<pre class="line-numbers language-js" data-language="js"><code class="language-js"><span class="token comment">/* function TreeNode(x) &#123;
    this.val = x;
    this.left = null;
    this.right = null;
&#125; */</span>

<span class="token keyword">function</span> <span class="token function">Convert</span><span class="token punctuation">(</span><span class="token parameter">pRootOfTree</span><span class="token punctuation">)</span> <span class="token punctuation">&#123;</span>
  <span class="token keyword">if</span> <span class="token punctuation">(</span><span class="token operator">!</span>pRootOfTree<span class="token punctuation">)</span> <span class="token punctuation">&#123;</span>
    <span class="token keyword">return</span> <span class="token keyword">null</span><span class="token punctuation">;</span>
  <span class="token punctuation">&#125;</span>
  <span class="token function">__Convert</span><span class="token punctuation">(</span>pRootOfTree<span class="token punctuation">,</span> <span class="token keyword">null</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
  <span class="token keyword">let</span> node <span class="token operator">=</span> pRootOfTree<span class="token punctuation">;</span>
  <span class="token keyword">while</span> <span class="token punctuation">(</span>node<span class="token punctuation">.</span>left<span class="token punctuation">)</span> <span class="token punctuation">&#123;</span>
    node <span class="token operator">=</span> node<span class="token punctuation">.</span>left<span class="token punctuation">;</span>
  <span class="token punctuation">&#125;</span>
  <span class="token keyword">return</span> node<span class="token punctuation">;</span>
<span class="token punctuation">&#125;</span>

<span class="token keyword">function</span> <span class="token function">__Convert</span><span class="token punctuation">(</span><span class="token parameter">pRootOfTree<span class="token punctuation">,</span> lastNodeInList <span class="token operator">=</span> <span class="token keyword">null</span></span><span class="token punctuation">)</span> <span class="token punctuation">&#123;</span>
  <span class="token keyword">if</span> <span class="token punctuation">(</span><span class="token operator">!</span>pRootOfTree<span class="token punctuation">)</span> <span class="token punctuation">&#123;</span>
    <span class="token keyword">return</span> <span class="token keyword">null</span><span class="token punctuation">;</span>
  <span class="token punctuation">&#125;</span>
  <span class="token comment">// step1:左子树</span>
  <span class="token keyword">if</span> <span class="token punctuation">(</span>pRootOfTree<span class="token punctuation">.</span>left<span class="token punctuation">)</span> <span class="token punctuation">&#123;</span>
    lastNodeInList <span class="token operator">=</span> <span class="token function">__Convert</span><span class="token punctuation">(</span>pRootOfTree<span class="token punctuation">.</span>left<span class="token punctuation">,</span> lastNodeInList<span class="token punctuation">)</span><span class="token punctuation">;</span>
  <span class="token punctuation">&#125;</span>
  <span class="token comment">// step2:当前节点</span>
  pRootOfTree<span class="token punctuation">.</span>left <span class="token operator">=</span> lastNodeInList<span class="token punctuation">;</span>
  <span class="token keyword">if</span> <span class="token punctuation">(</span>lastNodeInList<span class="token punctuation">)</span> <span class="token punctuation">&#123;</span>
    lastNodeInList<span class="token punctuation">.</span>right <span class="token operator">=</span> pRootOfTree<span class="token punctuation">;</span>
  <span class="token punctuation">&#125;</span>
  <span class="token comment">// step3:右子树</span>
  lastNodeInList <span class="token operator">=</span> pRootOfTree<span class="token punctuation">;</span>
  <span class="token keyword">if</span> <span class="token punctuation">(</span>pRootOfTree<span class="token punctuation">.</span>right<span class="token punctuation">)</span> <span class="token punctuation">&#123;</span>
    lastNodeInList <span class="token operator">=</span> <span class="token function">__Convert</span><span class="token punctuation">(</span>pRootOfTree<span class="token punctuation">.</span>right<span class="token punctuation">,</span> lastNodeInList<span class="token punctuation">)</span><span class="token punctuation">;</span>
  <span class="token punctuation">&#125;</span>

  <span class="token keyword">return</span> lastNodeInList<span class="token punctuation">;</span>
<span class="token punctuation">&#125;</span><span aria-hidden="true" class="line-numbers-rows"><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span></span></code></pre>

<h2 id="27-字符串的排列"><a href="#27-字符串的排列" class="headerlink" title="27.字符串的排列"></a>27.字符串的排列</h2><blockquote>
<p>输入一个字符串,按字典序打印出该字符串中字符的所有排列。例如输入字符串 abc,则打印出由字符 a,b,c 所能排列出来的所有字符串 abc,acb,bac,bca,cab 和 cba。</p>
<p>输入描述：输入一个字符串,长度不超过 9(可能有字符重复),字符只包括大小写字母。<br>解题思路：</p>
<p>abc 的所有组合可以这么理解：</p>
<p>每次取一个字符出来，比如’a’，然后剩下的字符组合成’bc’，’bc’的所有组合可以通过递归来获取，在 bc 的所有组合前面都拼接一个字符’a’；</p>
<p>再取出字符’b’，剩下的字符拼接成’ac’，同样的方法：’ac’的组合可以通过递归，在’ac’的所有组合前面都拼接一个字符’b’，</p>
<p>依次类推…</p>
<p>但是要<strong>注意</strong>：每次取出来的字符不能与前面的字符相同，所有用一个数组 map 来记录每次取出来的值</p>
</blockquote>
<pre class="line-numbers language-js" data-language="js"><code class="language-js"><span class="token keyword">function</span> <span class="token function">Permutation</span><span class="token punctuation">(</span><span class="token parameter">str</span><span class="token punctuation">)</span> <span class="token punctuation">&#123;</span>
  <span class="token comment">// write code here</span>
  <span class="token keyword">var</span> arr <span class="token operator">=</span> <span class="token punctuation">[</span><span class="token punctuation">]</span><span class="token punctuation">;</span>
  <span class="token keyword">if</span> <span class="token punctuation">(</span>str<span class="token punctuation">.</span>length <span class="token operator">===</span> <span class="token number">0</span><span class="token punctuation">)</span> <span class="token keyword">return</span> <span class="token punctuation">[</span><span class="token punctuation">]</span><span class="token punctuation">;</span>
  <span class="token keyword">if</span> <span class="token punctuation">(</span>str<span class="token punctuation">.</span>length <span class="token operator">===</span> <span class="token number">1</span><span class="token punctuation">)</span> <span class="token punctuation">&#123;</span>
    arr<span class="token punctuation">.</span><span class="token function">push</span><span class="token punctuation">(</span>str<span class="token punctuation">)</span><span class="token punctuation">;</span>
  <span class="token punctuation">&#125;</span> <span class="token keyword">else</span> <span class="token punctuation">&#123;</span>
    <span class="token keyword">var</span> map <span class="token operator">=</span> <span class="token punctuation">[</span><span class="token punctuation">]</span><span class="token punctuation">;</span> <span class="token comment">//用来判断是不是每次取出来的字符与前面取出来的是否有重复</span>
    <span class="token keyword">for</span> <span class="token punctuation">(</span><span class="token keyword">let</span> i <span class="token operator">=</span> <span class="token number">0</span><span class="token punctuation">;</span> i <span class="token operator">&lt;</span> str<span class="token punctuation">.</span>length<span class="token punctuation">;</span> i<span class="token operator">++</span><span class="token punctuation">)</span> <span class="token punctuation">&#123;</span>
      <span class="token keyword">var</span> s <span class="token operator">=</span> str<span class="token punctuation">[</span>i<span class="token punctuation">]</span><span class="token punctuation">;</span> <span class="token comment">// 索引为i的字符</span>
      <span class="token keyword">if</span> <span class="token punctuation">(</span><span class="token operator">!</span>map<span class="token punctuation">.</span><span class="token function">includes</span><span class="token punctuation">(</span>s<span class="token punctuation">)</span><span class="token punctuation">)</span> <span class="token punctuation">&#123;</span>
        <span class="token keyword">var</span> st <span class="token operator">=</span> str<span class="token punctuation">.</span><span class="token function">slice</span><span class="token punctuation">(</span><span class="token number">0</span><span class="token punctuation">,</span> i<span class="token punctuation">)</span> <span class="token operator">+</span> str<span class="token punctuation">.</span><span class="token function">slice</span><span class="token punctuation">(</span>i <span class="token operator">+</span> <span class="token number">1</span><span class="token punctuation">)</span><span class="token punctuation">;</span> <span class="token comment">// 剩下的字符拼接成一个新字符</span>
        <span class="token keyword">var</span> a <span class="token operator">=</span> <span class="token function">Permutation</span><span class="token punctuation">(</span>st<span class="token punctuation">)</span><span class="token punctuation">;</span> <span class="token comment">// 递归，找出新字符的排列组合</span>
        a<span class="token punctuation">.</span><span class="token function">forEach</span><span class="token punctuation">(</span><span class="token punctuation">(</span><span class="token parameter">ele</span><span class="token punctuation">)</span> <span class="token operator">=></span> arr<span class="token punctuation">.</span><span class="token function">push</span><span class="token punctuation">(</span>s <span class="token operator">+</span> ele<span class="token punctuation">)</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
      <span class="token punctuation">&#125;</span>
      map<span class="token punctuation">.</span><span class="token function">push</span><span class="token punctuation">(</span>s<span class="token punctuation">)</span><span class="token punctuation">;</span> <span class="token comment">//把s加入到map中</span>
    <span class="token punctuation">&#125;</span>
  <span class="token punctuation">&#125;</span>
  <span class="token keyword">return</span> arr<span class="token punctuation">;</span>
<span class="token punctuation">&#125;</span><span aria-hidden="true" class="line-numbers-rows"><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span></span></code></pre>

<h2 id="28-数组中出现次数超过一半的数字"><a href="#28-数组中出现次数超过一半的数字" class="headerlink" title="28.数组中出现次数超过一半的数字"></a>28.数组中出现次数超过一半的数字</h2><blockquote>
<p>数组中有一个数字出现的次数超过数组长度的一半，请找出这个数字。例如输入一个长度为 9 的数组[1,2,3,2,2,2,5,4,2]。由于数字 2 在数组中出现了 5 次，超过数组长度的一半，因此输出 2。如果不存在则输出 0。</p>
</blockquote>
<pre class="line-numbers language-js" data-language="js"><code class="language-js"><span class="token keyword">function</span> <span class="token function">MoreThanHalfNum_Solution</span><span class="token punctuation">(</span><span class="token parameter">numbers</span><span class="token punctuation">)</span> <span class="token punctuation">&#123;</span>
  <span class="token comment">// write code here</span>
  <span class="token keyword">var</span> len <span class="token operator">=</span> numbers<span class="token punctuation">.</span>length<span class="token punctuation">;</span>
  <span class="token keyword">var</span> obj <span class="token operator">=</span> <span class="token punctuation">&#123;</span><span class="token punctuation">&#125;</span><span class="token punctuation">;</span>
  numbers<span class="token punctuation">.</span><span class="token function">forEach</span><span class="token punctuation">(</span><span class="token punctuation">(</span><span class="token parameter">item</span><span class="token punctuation">)</span> <span class="token operator">=></span> <span class="token punctuation">&#123;</span>
    <span class="token keyword">if</span> <span class="token punctuation">(</span><span class="token operator">!</span>obj<span class="token punctuation">[</span>item<span class="token punctuation">]</span><span class="token punctuation">)</span> <span class="token punctuation">&#123;</span>
      obj<span class="token punctuation">[</span>item<span class="token punctuation">]</span> <span class="token operator">=</span> <span class="token number">1</span><span class="token punctuation">;</span>
    <span class="token punctuation">&#125;</span> <span class="token keyword">else</span> <span class="token punctuation">&#123;</span>
      obj<span class="token punctuation">[</span>item<span class="token punctuation">]</span><span class="token operator">++</span><span class="token punctuation">;</span>
    <span class="token punctuation">&#125;</span>
  <span class="token punctuation">&#125;</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
  <span class="token keyword">for</span> <span class="token punctuation">(</span><span class="token keyword">let</span> key <span class="token keyword">in</span> obj<span class="token punctuation">)</span> <span class="token punctuation">&#123;</span>
    <span class="token keyword">if</span> <span class="token punctuation">(</span>obj<span class="token punctuation">[</span>key<span class="token punctuation">]</span> <span class="token operator">></span> len <span class="token operator">/</span> <span class="token number">2</span><span class="token punctuation">)</span> <span class="token punctuation">&#123;</span>
      <span class="token keyword">return</span> key<span class="token punctuation">;</span>
    <span class="token punctuation">&#125;</span>
  <span class="token punctuation">&#125;</span>
  <span class="token keyword">return</span> <span class="token number">0</span><span class="token punctuation">;</span>
<span class="token punctuation">&#125;</span><span aria-hidden="true" class="line-numbers-rows"><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span></span></code></pre>

<h2 id="29-最小的-K-个数"><a href="#29-最小的-K-个数" class="headerlink" title="29.最小的 K 个数"></a>29.最小的 K 个数</h2><blockquote>
<p>输入 n 个整数，找出其中最小的 K 个数。例如输入 4,5,1,6,2,7,3,8 这 8 个数字，则最小的 4 个数字是 1,2,3,4,。<br>方法一：快排</p>
</blockquote>
<pre class="line-numbers language-js" data-language="js"><code class="language-js"><span class="token keyword">function</span> <span class="token function">GetLeastNumbers_Solution</span><span class="token punctuation">(</span><span class="token parameter">input<span class="token punctuation">,</span> k</span><span class="token punctuation">)</span> <span class="token punctuation">&#123;</span>
  <span class="token comment">// write code here</span>
  <span class="token keyword">if</span> <span class="token punctuation">(</span>k <span class="token operator">></span> input<span class="token punctuation">.</span>length<span class="token punctuation">)</span> <span class="token keyword">return</span> <span class="token punctuation">[</span><span class="token punctuation">]</span><span class="token punctuation">;</span>
  <span class="token function">quickSort</span><span class="token punctuation">(</span>input<span class="token punctuation">)</span><span class="token punctuation">;</span>
  <span class="token keyword">return</span> input<span class="token punctuation">.</span><span class="token function">slice</span><span class="token punctuation">(</span><span class="token number">0</span><span class="token punctuation">,</span> k<span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token punctuation">&#125;</span>

<span class="token keyword">function</span> <span class="token function">quickSort</span><span class="token punctuation">(</span><span class="token parameter">input<span class="token punctuation">,</span> left <span class="token operator">=</span> <span class="token number">0</span><span class="token punctuation">,</span> right <span class="token operator">=</span> input<span class="token punctuation">.</span>length <span class="token operator">-</span> <span class="token number">1</span></span><span class="token punctuation">)</span> <span class="token punctuation">&#123;</span>
  <span class="token keyword">if</span> <span class="token punctuation">(</span>left <span class="token operator">>=</span> right<span class="token punctuation">)</span> <span class="token keyword">return</span><span class="token punctuation">;</span>
  <span class="token keyword">var</span> baseId <span class="token operator">=</span> left<span class="token punctuation">;</span>
  <span class="token keyword">var</span> baseVal <span class="token operator">=</span> input<span class="token punctuation">[</span>baseId<span class="token punctuation">]</span><span class="token punctuation">;</span>
  <span class="token keyword">var</span> i <span class="token operator">=</span> left<span class="token punctuation">;</span>
  <span class="token keyword">var</span> j <span class="token operator">=</span> right<span class="token punctuation">;</span>
  <span class="token keyword">while</span> <span class="token punctuation">(</span>i <span class="token operator">&lt;</span> j<span class="token punctuation">)</span> <span class="token punctuation">&#123;</span>
    <span class="token keyword">while</span> <span class="token punctuation">(</span>j <span class="token operator">></span> i <span class="token operator">&amp;&amp;</span> input<span class="token punctuation">[</span>j<span class="token punctuation">]</span> <span class="token operator">>=</span> baseVal<span class="token punctuation">)</span> <span class="token punctuation">&#123;</span>
      j<span class="token operator">--</span><span class="token punctuation">;</span>
    <span class="token punctuation">&#125;</span>
    <span class="token keyword">while</span> <span class="token punctuation">(</span>i <span class="token operator">&lt;</span> j <span class="token operator">&amp;&amp;</span> input<span class="token punctuation">[</span>i<span class="token punctuation">]</span> <span class="token operator">&lt;=</span> baseVal<span class="token punctuation">)</span> <span class="token punctuation">&#123;</span>
      i<span class="token operator">++</span><span class="token punctuation">;</span>
    <span class="token punctuation">&#125;</span>
    <span class="token punctuation">[</span>input<span class="token punctuation">[</span>i<span class="token punctuation">]</span><span class="token punctuation">,</span> input<span class="token punctuation">[</span>j<span class="token punctuation">]</span><span class="token punctuation">]</span> <span class="token operator">=</span> <span class="token punctuation">[</span>input<span class="token punctuation">[</span>j<span class="token punctuation">]</span><span class="token punctuation">,</span> input<span class="token punctuation">[</span>i<span class="token punctuation">]</span><span class="token punctuation">]</span><span class="token punctuation">;</span>
  <span class="token punctuation">&#125;</span>
  <span class="token punctuation">[</span>input<span class="token punctuation">[</span>baseId<span class="token punctuation">]</span><span class="token punctuation">,</span> input<span class="token punctuation">[</span>j<span class="token punctuation">]</span><span class="token punctuation">]</span> <span class="token operator">=</span> <span class="token punctuation">[</span>input<span class="token punctuation">[</span>j<span class="token punctuation">]</span><span class="token punctuation">,</span> input<span class="token punctuation">[</span>baseId<span class="token punctuation">]</span><span class="token punctuation">]</span><span class="token punctuation">;</span>
  <span class="token function">quickSort</span><span class="token punctuation">(</span>input<span class="token punctuation">,</span> left<span class="token punctuation">,</span> j <span class="token operator">-</span> <span class="token number">1</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
  <span class="token function">quickSort</span><span class="token punctuation">(</span>input<span class="token punctuation">,</span> j <span class="token operator">+</span> <span class="token number">1</span><span class="token punctuation">,</span> right<span class="token punctuation">)</span><span class="token punctuation">;</span>
  <span class="token keyword">return</span> input<span class="token punctuation">;</span>
<span class="token punctuation">&#125;</span><span aria-hidden="true" class="line-numbers-rows"><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span></span></code></pre>

<blockquote>
<p>方法二：冒泡排序</p>
</blockquote>
<pre class="line-numbers language-js" data-language="js"><code class="language-js"><span class="token keyword">function</span> <span class="token function">GetLeastNumbers_Solution</span><span class="token punctuation">(</span><span class="token parameter">input<span class="token punctuation">,</span> k</span><span class="token punctuation">)</span> <span class="token punctuation">&#123;</span>
  <span class="token comment">// write code here</span>
  <span class="token keyword">if</span> <span class="token punctuation">(</span>k <span class="token operator">></span> input<span class="token punctuation">.</span>length<span class="token punctuation">)</span> <span class="token keyword">return</span> <span class="token punctuation">[</span><span class="token punctuation">]</span><span class="token punctuation">;</span>
  <span class="token keyword">for</span> <span class="token punctuation">(</span><span class="token keyword">let</span> j <span class="token operator">=</span> input<span class="token punctuation">.</span>length <span class="token operator">-</span> <span class="token number">1</span><span class="token punctuation">;</span> j <span class="token operator">>=</span> input<span class="token punctuation">.</span>length <span class="token operator">-</span> k<span class="token punctuation">;</span> j<span class="token operator">--</span><span class="token punctuation">)</span> <span class="token punctuation">&#123;</span>
    <span class="token keyword">for</span> <span class="token punctuation">(</span><span class="token keyword">let</span> i <span class="token operator">=</span> <span class="token number">0</span><span class="token punctuation">;</span> i <span class="token operator">&lt;</span> j<span class="token punctuation">;</span> i<span class="token operator">++</span><span class="token punctuation">)</span> <span class="token punctuation">&#123;</span>
      <span class="token keyword">if</span> <span class="token punctuation">(</span>input<span class="token punctuation">[</span>i<span class="token punctuation">]</span> <span class="token operator">&lt;</span> input<span class="token punctuation">[</span>i <span class="token operator">+</span> <span class="token number">1</span><span class="token punctuation">]</span><span class="token punctuation">)</span> <span class="token punctuation">&#123;</span>
        <span class="token punctuation">[</span>input<span class="token punctuation">[</span>i<span class="token punctuation">]</span><span class="token punctuation">,</span> input<span class="token punctuation">[</span>i <span class="token operator">+</span> <span class="token number">1</span><span class="token punctuation">]</span><span class="token punctuation">]</span> <span class="token operator">=</span> <span class="token punctuation">[</span>input<span class="token punctuation">[</span>i <span class="token operator">+</span> <span class="token number">1</span><span class="token punctuation">]</span><span class="token punctuation">,</span> input<span class="token punctuation">[</span>i<span class="token punctuation">]</span><span class="token punctuation">]</span><span class="token punctuation">;</span>
      <span class="token punctuation">&#125;</span>
    <span class="token punctuation">&#125;</span>
  <span class="token punctuation">&#125;</span>
  <span class="token keyword">var</span> res <span class="token operator">=</span> <span class="token punctuation">[</span><span class="token punctuation">]</span><span class="token punctuation">;</span>
  <span class="token keyword">while</span> <span class="token punctuation">(</span>k <span class="token operator">></span> <span class="token number">0</span><span class="token punctuation">)</span> <span class="token punctuation">&#123;</span>
    res<span class="token punctuation">.</span><span class="token function">push</span><span class="token punctuation">(</span>input<span class="token punctuation">.</span><span class="token function">pop</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
    k<span class="token operator">--</span><span class="token punctuation">;</span>
  <span class="token punctuation">&#125;</span>
  <span class="token keyword">return</span> res<span class="token punctuation">;</span>
<span class="token punctuation">&#125;</span><span aria-hidden="true" class="line-numbers-rows"><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span></span></code></pre>

<blockquote>
<p>方法三：sort 排序</p>
</blockquote>
<pre class="line-numbers language-js" data-language="js"><code class="language-js"><span class="token keyword">function</span> <span class="token function">GetLeastNumbers_Solution</span><span class="token punctuation">(</span><span class="token parameter">input<span class="token punctuation">,</span> k</span><span class="token punctuation">)</span> <span class="token punctuation">&#123;</span>
  <span class="token comment">// write code here</span>
  <span class="token keyword">if</span> <span class="token punctuation">(</span>input<span class="token punctuation">.</span>length <span class="token operator">&lt;</span> k<span class="token punctuation">)</span> <span class="token punctuation">&#123;</span>
    <span class="token keyword">return</span> <span class="token punctuation">[</span><span class="token punctuation">]</span><span class="token punctuation">;</span>
  <span class="token punctuation">&#125;</span>
  input<span class="token punctuation">.</span><span class="token function">sort</span><span class="token punctuation">(</span><span class="token punctuation">(</span><span class="token parameter">a<span class="token punctuation">,</span> b</span><span class="token punctuation">)</span> <span class="token operator">=></span> a <span class="token operator">-</span> b<span class="token punctuation">)</span><span class="token punctuation">;</span>
  <span class="token keyword">return</span> input<span class="token punctuation">.</span><span class="token function">slice</span><span class="token punctuation">(</span><span class="token number">0</span><span class="token punctuation">,</span> k<span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token punctuation">&#125;</span><span aria-hidden="true" class="line-numbers-rows"><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span></span></code></pre>

<h2 id="30-连续子数组的最大和"><a href="#30-连续子数组的最大和" class="headerlink" title="30.连续子数组的最大和"></a>30.连续子数组的最大和</h2><blockquote>
<p>HZ 偶尔会拿些专业问题来忽悠那些非计算机专业的同学。今天测试组开完会后,他又发话了:在古老的一维模式识别中,常常需要计算连续子向量的最大和,当向量全为正数的时候,问题很好解决。但是,如果向量中包含负数,是否应该包含某个负数,并期望旁边的正数会弥补它呢？例如:{6,-3,-2,7,-15,1,2,2},连续子向量的最大和为 8(从第 0 个开始,到第 3 个为止)。给一个数组，返回它的最大连续子序列的和，你会不会被他忽悠住？(子向量的长度至少是 1)</p>
</blockquote>
<pre class="line-numbers language-js" data-language="js"><code class="language-js"><span class="token comment">/*
举例：array = [1, -2, 3, 10, -4, 7, 2, -5]
初始化 max = 1, temp = 1
i = 1时， temp = -1, max = 1
i = 2时， temp = 3,  max = 3
i = 3时， temp = 13, max = 13
i = 4时， temp = 9 , max = 13
i = 5时， temp = 16, max = 16
i = 6时， temp = 18, max = 18
i = 7时， temp = 13, max = 18;
*/</span>

<span class="token keyword">function</span> <span class="token function">FindGreatestSumOfSubArray</span><span class="token punctuation">(</span><span class="token parameter">array</span><span class="token punctuation">)</span> <span class="token punctuation">&#123;</span>
  <span class="token comment">// write code here</span>
  <span class="token keyword">var</span> max <span class="token operator">=</span> array<span class="token punctuation">[</span><span class="token number">0</span><span class="token punctuation">]</span><span class="token punctuation">,</span>
    temp <span class="token operator">=</span> array<span class="token punctuation">[</span><span class="token number">0</span><span class="token punctuation">]</span><span class="token punctuation">;</span>
  <span class="token keyword">for</span> <span class="token punctuation">(</span><span class="token keyword">let</span> i <span class="token operator">=</span> <span class="token number">1</span><span class="token punctuation">;</span> i <span class="token operator">&lt;</span> array<span class="token punctuation">.</span>length<span class="token punctuation">;</span> i<span class="token operator">++</span><span class="token punctuation">)</span> <span class="token punctuation">&#123;</span>
    <span class="token keyword">if</span> <span class="token punctuation">(</span>temp <span class="token operator">&lt;=</span> <span class="token number">0</span><span class="token punctuation">)</span> <span class="token punctuation">&#123;</span>
      temp <span class="token operator">=</span> array<span class="token punctuation">[</span>i<span class="token punctuation">]</span><span class="token punctuation">;</span>
    <span class="token punctuation">&#125;</span> <span class="token keyword">else</span> <span class="token punctuation">&#123;</span>
      temp <span class="token operator">+=</span> array<span class="token punctuation">[</span>i<span class="token punctuation">]</span><span class="token punctuation">;</span>
    <span class="token punctuation">&#125;</span>
    <span class="token keyword">if</span> <span class="token punctuation">(</span>temp <span class="token operator">></span> max<span class="token punctuation">)</span> <span class="token punctuation">&#123;</span>
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    <span class="token punctuation">&#125;</span>
  <span class="token punctuation">&#125;</span>
  <span class="token keyword">return</span> max<span class="token punctuation">;</span>
<span class="token punctuation">&#125;</span><span aria-hidden="true" class="line-numbers-rows"><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span></span></code></pre>

<ul>
<li>动态规划</li>
</ul>
<pre class="line-numbers language-txt" data-language="txt"><code class="language-txt">dp[i] 定义为以 nums[i] 结尾的最大子数组的和，状态转移方程：
dp[i] &#x3D; max&#123; dp[i-1] + nums[i], nums[i] &#125;     表示要么自成一派，要么和前面的子数组合并
连续子数组的最大和一定是 dp 数组的最大值<span aria-hidden="true" class="line-numbers-rows"><span></span><span></span><span></span></span></code></pre>

<pre class="line-numbers language-js" data-language="js"><code class="language-js"><span class="token keyword">var</span> <span class="token function-variable function">maxSubArray</span> <span class="token operator">=</span> <span class="token keyword">function</span> <span class="token punctuation">(</span><span class="token parameter">nums</span><span class="token punctuation">)</span> <span class="token punctuation">&#123;</span>
    <span class="token keyword">let</span> len <span class="token operator">=</span> nums<span class="token punctuation">.</span>length<span class="token punctuation">;</span>
    <span class="token keyword">let</span> dp <span class="token operator">=</span> <span class="token punctuation">[</span><span class="token punctuation">]</span><span class="token punctuation">;</span>
    dp<span class="token punctuation">[</span><span class="token number">0</span><span class="token punctuation">]</span> <span class="token operator">=</span> nums<span class="token punctuation">[</span><span class="token number">0</span><span class="token punctuation">]</span><span class="token punctuation">;</span>
    <span class="token keyword">for</span> <span class="token punctuation">(</span><span class="token keyword">let</span> i <span class="token operator">=</span> <span class="token number">1</span><span class="token punctuation">;</span> i <span class="token operator">&lt;</span> len<span class="token punctuation">;</span> i<span class="token operator">++</span><span class="token punctuation">)</span> <span class="token punctuation">&#123;</span>
        dp<span class="token punctuation">[</span>i<span class="token punctuation">]</span> <span class="token operator">=</span> Math<span class="token punctuation">.</span><span class="token function">max</span><span class="token punctuation">(</span>dp<span class="token punctuation">[</span>i <span class="token operator">-</span> <span class="token number">1</span><span class="token punctuation">]</span> <span class="token operator">+</span> nums<span class="token punctuation">[</span>i<span class="token punctuation">]</span><span class="token punctuation">,</span> nums<span class="token punctuation">[</span>i<span class="token punctuation">]</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
    <span class="token punctuation">&#125;</span>
    <span class="token keyword">return</span> Math<span class="token punctuation">.</span><span class="token function">max</span><span class="token punctuation">(</span><span class="token operator">...</span>dp<span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token punctuation">&#125;</span><span class="token punctuation">;</span><span aria-hidden="true" class="line-numbers-rows"><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span><span></span></span></code></pre>

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